Occasionally

In an occasional manner; on occasion; at times, as convenience requires or opportunity offers; not regularly.

sporadically and infrequently; "he was arrogant and occasionally callous"; "open areas are only occasionally interrupted by clumps of trees"; "they visit New York on occasion"; "now and again she would take her favorite book from the shelf and read to us"; "as we drove along, the beautiful scenery now and then attracted his attention"